Airbag and airbag apparatus

ABSTRACT

An airbag has an inflator at a base side thereof, and the inflator ejects gas to inflate the airbag such that a distal side thereof is deployed in a direction away from the base side. The airbag includes a left half airbag to be deployed on a left side of an occupant and a right half airbag to be deployed on a right side of the occupant. The airbag further includes a constraining device for constraining lateral widths of the left half airbag and the right half airbag when the airbag is deployed.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

[0001] The present invention relates to an airbag and an airbagapparatus for protecting an occupant in case of vehicle collision or thelike. More specifically, the present invention relates to an airbag andan airbag apparatus having a left half airbag and a right half airbag tobe deployed on a left side and a right side of the occupant,respectively.

[0002] As an airbag for protecting an occupant in case of vehiclecollision or the like, Japanese Patent Publication (KOKAI) No. 04-292239has disclosed an airbag having a left half airbag and a right halfairbag to be deployed on a left side and a right side of the occupant bya common inflator, respectively. In the airbag of the publication, theleft half airbag and the right half airbag are connected at distal endsthereof by a tie panel.

[0003] The airbag is folded and stored in a case, and covered by acover. When the inflator (gas generator) is actuated to eject gas uponvehicle collision, the airbag is deployed in front of the occupant whilepushing and opening the cover.

[0004] The inflator is disposed inside or outside of the airbag at abase side thereof. In an airbag apparatus having the inflator disposedoutside the airbag, the gas from the inflator is supplied into theairbag through a gas inlet provided in the airbag at the base side. Inan airbag having the inflator disposed inside the airbag, the entireinflator may be disposed in the air bag, or a part of the inflator maybe disposed in the airbag. As an example of the latter, an airbagincludes a pair of slit openings, and a rod-shaped inflator is insertedinto the slit openings with both ends thereof projecting out from theairbag.

[0005] In the airbag having the left half airbag and the right halfairbag disclosed in Japanese Patent Publication No. 04-292239, when theleft half airbag and the right half airbag have large capacities in theinflated state, it is necessary to employ an inflator having a largecapacity in order to deploy the airbag quickly.

[0006] In the airbag disclosed in Japanese Patent Publication No.04-292239, the left half airbag and the right half airbag are connectedat the distal ends by the tie panel. Therefore, when the airbag isdeployed, the tie panel receives a lateral center of the body of theoccupant.

[0007] In the airbag disclosed in Japanese Patent Publication No.04-292239, when the left half airbag and the right half airbag aredeployed, one of the airbags may receive more gas from the inflator, andthus the other airbag may be inflated later than the one of the airbags.In the airbag disclosed in the publication, the left half airbag and theright half airbag are connected by the tie panel. Thus, it is expectedthat even when one of the airbags is inflated later, the other of theairbags may pull and facilitate the one of the airbags to be deployedvia the tie panel in a direction that the airbag deploys. However, thetie panel connects the left half airbag and the right half airbag at thedistal ends thereof. Therefore, the one of the airbags can pull theother of the airbags sufficiently via the tie panel only after the oneof the airbags is deployed up to the distal end.

[0008] It is an object of the present invention to provide an airbag andan airbag apparatus in which a left half airbag and a right half airbagare deployed sufficiently quickly even when an inflator has a relativelysmall capacity.

[0009] It is another object of the present invention to provide anairbag and an airbag apparatus in which the left half airbag receives aleft thorax of the occupant, the right half airbag receives a rightthorax, and a space between the half airbags faces the center of thethorax of the occupant.

[0010] It is a further object of the present invention to provide anairbag and an airbag apparatus in which both of the left half airbag andthe right half airbag are deployed smoothly and substantiallysymmetrically from an early stage of the deployment.

[0011] Further objects and advantages of the invention will be apparentfrom the following description of the invention.

SUMMARY OF THE INVENTION

[0012] According to the present invention, an airbag has an inflator ata base side thereof, and the inflator ejects gas to inflate the airbagsuch that a distal side thereof is deployed in a direction away from thebase side. The airbag includes a left half airbag to be deployed on aleft side of an occupant and a right half airbag to be deployed on aright side of the occupant. The airbag further includes constrainingmeans for constraining lateral widths of the left half airbag and theright half airbag when the airbag is deployed.

[0013] According to the present invention, an airbag apparatus includesthe airbag described above and the inflator for deploying the airbag.

[0014] In the present invention, the airbag and the airbag apparatusinclude the constraining means for constraining the lateral widththereof when the airbag is deployed. Therefore, even when the inflatorhas a small capacity, the left half airbag and the right half airbag aredeployed sufficiently quickly. The width constraining means may be astring. With this arrangement, it is possible to set the widths of theleft half airbag and the right half airbag at a desired value in theinflated state. Alternatively, the width constraining means may bejoining means (for example stitching) for joining panels of the lefthalf airbag and the right half airbag with each other. With thisarrangement, the left half airbag and the right half airbag havesufficiently small capacities in the inflated state.

[0015] In the present invention, a vertical width or height of theairbag may be constrained in addition to the lateral width describedabove when the airbag is deployed. With this arrangement, the left halfand the right half airbags may be deployed further quickly.

[0016] In the present invention, the distal ends of the left half airbagand the right half airbag are not connected with each other, and a spaceopening toward the occupant is formed between the distal ends of theleft half airbag and the right half airbag when the airbag is deployed.When the airbag is deployed, the left half airbag receives the leftthorax of the occupant, and the right half airbag receives the rightthorax of the occupant. The left and right thoraxes include hard strongrib bones. The airbag receives and absorbs an impact of the occupantthrough the rib bones. The airbag includes the space between the distalends of the left half airbag and the right half airbag in the deployedstate, so that the space faces a central portion of the thorax of theoccupant near breastbones. Therefore, when the occupant hits the airbag,the portion around the breastbones of the thorax does not receive astrong force from the airbag, and thus a load exerted to the portionaround the breastbones is reduced.

[0017] According to the present invention, a distance between the distalends of the left half airbag and the right half airbag is set to be150-350 mm when the airbag is deployed. As a result, the left halfairbag faces a portion around a center of the left thorax, and the righthalf airbag faces a portion around a center of the right thorax.Accordingly, the airbag reliably receives the portion around the ribbones of the upper body of the occupant.

[0018] In the present invention, a common inflator may be provided forinflating the left half airbag and the right half airbag. With thisarrangement, it is possible to reduce the number of the inflators,thereby reducing a manufacturing cost.

[0019] According to the present invention, the left half airbag and theright half airbag may be connected with each other at midsectionsthereof in a direction that the airbag deploys. When the half airbagsare connected at the midsections, even if one of the airbags is deployedlater, the other of the airbags pulls the one of the airbags tofacilitate the deployment. The left half airbag and the right halfairbag are connected at the midsections in the direction of deployment.Accordingly, the other of the airbags starts to pull the one of theairbags from an early stage when the other of the airbags is deployed upto the midsection. Therefore, both of the left half airbag and the righthalf airbag are deployed smoothly and substantially symmetrically fromthe early stage of deployment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIGS. 1(a) and 1(b) are views of an airbag according to anembodiment of the present invention, wherein FIG. 1(a) is a perspectiveview of the airbag in a deployed state, and FIG. 1(b) is a crosssectional view taken along line 1(b)-1(b) in FIG. 1(a);

[0021]FIG. 2 is a cross sectional view of the airbag taken along line2-2 in FIG. 1(b);

[0022]FIG. 3 is a cross sectional view of the airbag taken along line3-3 in FIG. 1(b);

[0023] FIGS. 4(a) and 4(b) are views of the airbag shown in FIG. 1(a),wherein FIG. 4(a) is an exploded perspective view of the airbag, andFIG. 4(b) is an enlarged view of a portion 4(b) in FIG. 4(a);

[0024]FIG. 5 is a cross sectional perspective view of an airbagaccording to another embodiment;

[0025]FIG. 6 is a cross-sectional perspective view of an airbagaccording to a further embodiment;

[0026] FIGS. 7(a) and 7(b) are views of an airbag according to a stillfurther embodiment, wherein FIG. 7(a) is a perspective view of theairbag tightened by a belt, and FIG. 7(b) is a cross-sectionalperspective view of a portion at which the belt is provided;

[0027] FIGS. 8(a) and 8(b) are views of an airbag according to a stillfurther embodiment, wherein FIG. 8(a) is a perspective view of theairbag, and FIG. 8(b) is a cross sectional view of the airbag takenalong line 8(b)-8(b) in FIG. 8(a);

[0028]FIG. 9 is an explanatory view showing an airbag according to astill further embodiment; and

[0029]FIG. 10 is an explanatory view showing an airbag according to astill further embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] Hereunder, embodiments of the present invention will be describedwith reference to the accompanying drawings. FIG. 1(a) is a perspectiveview of an airbag according to an embodiment of the present invention ina deployed state, and FIG. 1(b) is a cross sectional view taken alongline 1(b)-1(b) in FIG. 1(a). FIG. 2 is a cross sectional view of theairbag taken along line 2-2 in FIG. 1(b). FIG. 3 is a cross sectionalview of the airbag taken along line 3-3 in FIG. 1(b). FIG. 4(a) is anexploded perspective view of the airbag, and FIG. 4(b) is an enlargedview showing a portion 4(b) in FIG. 4(a).

[0031] An airbag 10 includes a right half airbag 12 to be deployed on aright front side of an occupant, a left half airbag 14 to be deployed ona left front side of the occupant, and a communicating portion 16 forcommunicating end portions of the right half airbag 12 and the left halfairbag 14 with each other. The communication portion 16 corresponds to abase side of the airbag 10. The right half airbag 12 and the left halfairbag 14 are deployed in the direction away from the communicatingportion 16, respectively.

[0032] The right half airbag 12 and the left half airbag 14 are providedwith string-shaped (band-shaped) connecting belts 70 as widthconstraining means for constraining lateral widths of the half airbagswhen the airbag is deployed. The connecting belts 70 are disposed insidethe right half airbag 12 and the left half airbag 14, and connect frontinner panels 22, 24 and front outer panels 26, 28 constituting right andleft side surfaces of the right half airbag 12 and the left half airbag14, respectively. The connecting belts 70 are joined to the respectivepanels 22-28 at both ends thereof by seams 72.

[0033] When the right half airbag 12 and the left half airbag 14 aredeployed, the connecting belts 70 prevent the right and left sidesurfaces of the right half airbag 12 and the left half airbag 14 frommoving away from each other more than lengths of the connecting belts70. Accordingly, the lateral widths of the right half airbag 12 and theleft half airbag 14 are constrained, when the airbag is deployed.

[0034] When the airbag 10 is deployed, a bridging member such as a tiepanel does not exist between distal ends of the right half airbag 12 andthe left half airbag 14, and a space 13 is formed between the distalends of both bags 12, 14 to face the occupant (upward in FIG. 1(b)).

[0035] When the airbag 10 is completely deployed, a distance W betweenan extremity 12 t of the right half airbag 12 and an extremity 14 t ofthe left half airbag 14 is preferably 150 to 350 mm, and morepreferably, 170 to 330 mm. In the airbag 10, the right half airbag 12and the left half airbag 14 are connected with seams 52 at midsectionsthereof in a direction that the airbag deploys.

[0036] In this embodiment, the airbag 10 is formed by stitching panels18, 20, 22, 24, 26, 28 and the pair of connecting belts 70 together. Aconstruction of stitching between the panels will be described in detailnext. As shown in FIG. 4(a), the panel 18 (rear inner panel) constitutesa center surface of the communicating portion 16 and rear end surfacesof the right half airbag 12 and the left half airbag 14 from themidsections thereof in the direction of deployment. The panel 20 (rearouter panel) constitutes a surface opposite to the rear inner panel 18(outer surface of the airbag).

[0037] The panels 22, 24 (front inner panels) constitute front centersurfaces of the right half airbag 12 and the left half airbag 14 fromthe midsections in the direction of deployment (opposing surfaces of theright half airbag 12 and the left half airbag 14). The panels 26, 28(front outer panels) constitute surfaces opposite to the front innerpanels 22, 24 (outer surfaces of the airbag). In other words, the frontinner panels 22, 24 and the front outer panels 26, 28 constitute bothside surfaces of the right half airbag 12 and the left half airbag 14,respectively.

[0038] As described above, the connecting belts 70 connect the frontinner panel 22 and the front outer panel 26 of the right half airbag 12,and the front inner panel 24 and the front outer panel 28 of the lefthalf airbag 14, respectively. Seams 30 (sewing thread) join the rearinner panel 18 and the rear outer panel 20, and seams 32, 34 join therear inner panel 18 and the front inner panels 22, 24, respectively.Seams 36, 38 join the rear outer panel 20 and the front outer panels 26,28, and seams 72 join the both ends of the connecting belts 70, thefront inner panels 22, 24, and the front outer panels 26, 28. A venthole 28 a is provided in the front outer panel of the left half airbag.A similar vent hole (not shown) is provided in the front outer panel 26of the right half airbag.

[0039] As shown in FIG. 1(a), seam allowances (joint allowances) 44, 46are disposed between the rear inner panel 18 and the front inner panels22, 24, and are exposed on the outer surfaces of the right half airbag12 and the left half airbag 14. As shown in FIG. 1(b) and FIG. 3,tongue-shaped joint allowances 48, 50 (only the joint allowance 48 isshown in FIG. 3) extend from the seam allowances 44, 46. As shown inFIG. 1(b), the seams 52 stitch the joint allowances 48, 50 together.

[0040] With this arrangement, the right half airbag 12 and the left halfairbag 14 are connected with each other at the midsections in thedirection of deployment at the seam allowances 44, 46 disposed betweenthe rear inner panel 18 and the front inner panels 22, 24. A distancebetween a rear end 10 e of the deployed airbag and the seams 52 ispreferably 30 to 70%, more preferably 40 to 55%, of a length L of thedeployed airbag 10 in the front-to-rear direction.

[0041] The rear outer panel 20 constituting the outer surface of thecommunicating portion 16 is provided with a pair of slits 54 forinserting the inflator. In this embodiment, as shown in FIGS. 1(a) and1(b), a rod-shaped inflator 56 is employed. The inflator 56 is insertedinto the slits 54 so as to pass through the communicating portion 16 inthe width direction of the vehicle, and both ends of the inflator 56 aredisposed outside the airbag 10.

[0042] The airbag 10 is mounted to an airbag apparatus for protectingthe occupant in case of vehicle collision. The airbag apparatus includesa case (not shown) in a box shape with no lid for storing the airbag 10,and the airbag 10 is connected to the case. As shown in FIG. 1(b), holes58 are formed in the airbag for inserting a fastener (not shown) such asbolt for connecting the airbag 10 to the case. The inflator 56 isattached to the interior of the case at both ends thereof.

[0043] The airbag apparatus is constructed such that the airbag 10 isfolded and stored in the case, and a cover (not shown) such as a lid isattached to the case so as to cover the folded airbag 10. The airbag 10presses and breaks the lid when the airbag is deployed.

[0044] The airbag apparatus is mounted in, for example, an instrumentpanel in front of a front seat of the motor vehicle. In case of vehiclecollision, the inflator 56 is activated and ejects gas, so that the gasis ejected from the inflator 56 into the communicating portion 16. Thegas from the inflator 56 flows from the communicating portion 16 intothe right half airbag 12 and the left half airbag 14, and deploys theright half airbag 12 and the left half airbag 14 on the right front sideand the left front side of the occupant, respectively.

[0045] In the airbag 10, the lateral widths of the right half airbag 12and the left half airbag 14 are constrained by the connecting belts 70,respectively, when the airbag is deployed. Accordingly, the right halfairbag 12 and the left half airbag 14 have relatively small capacities.Therefore, even when the inflator 56 has a relatively small capacity,the right half airbag 12 and the left half airbag 14 are deployedsufficiently quickly.

[0046] In this embodiment, the right and left side surfaces of the righthalf airbag 12 and the left half airbag 14 move away from each other bythe length of the connecting belts 70, respectively. Accordingly, theright half airbag 12 and the left half airbag 14 have certainthicknesses even at the portions where the side surfaces are connectedby the connecting belts 70.

[0047] In the airbag 10, when the right half airbag 12 and the left halfairbag 14 are deployed from the folded state, even if one of the airbags12, 14 is deployed faster and the other of the airbags 12, 14 isdeployed slower, the one of the airbags pulls the other of the airbagsto facilitate the deployment, as the right half airbag 12 and the lefthalf airbag 14 are connected. In addition, the right half airbag 12 andthe left half airbag 14 are connected with each other at the midsectionsthereof in the direction of deployment by the seams 52. Therefore, theone of the airbags starts to pull the other of the airbags in thedirection of deployment from a relatively early stage once thedeployment starts. Accordingly, both of the right half airbag 12 and theleft half airbag 14 are deployed smoothly and substantiallysymmetrically from the early stage of deployment.

[0048] When the airbag 10 is completely deployed, the space 13 is formedbetween the distal ends of the right half airbag 12 and the left halfairbag 14, and the space 13 faces the occupant. The right half airbag 12receives the right thorax of the occupant, the left half airbag 14receives the left thorax, and the space 13 faces the portion around thebreastbones. Therefore, a reaction force exerted on the portion aroundthe breastbones is reduced when the airbag receives the occupant.

[0049] The airbag 10 is manufactured in the following procedure. Asshown in FIG. 4(a), the rear inner panel 18 and the front inner panels22, 24 are stitched together by the seams 32, 34, and the rear outerpanel 20 and the front outer panels 26, 28 are stitched together by theseams 36, 38. In this case, the seam allowances 44, 46 between the rearinner panel 18 and the front inner panels 22, 24 are disposed on theside exposed to the outside of the airbag in the finished state as anairbag product.

[0050] In this embodiment, as shown in FIG. 4(b), at the seam allowance44 of the rear inner panel 18 and the front inner panel 22, the rearinner panel 18 and the front inner panel 22 are stitched by the seams 32(32 a, 32 b) only at both ends of the seam allowance 44, respectively.An opening 60 for reversing the airbag is formed between the seams 32 a,32 b.

[0051] In the finished state as an airbag product, a stitched body ofthe rear inner panel 18 and the front inner panels 22, 24 and a stitchedbody of the rear outer panel 20 and the front outer panels 26, 28 aresuperimposed and stitched together by the seams 30, 40, 42 aroundperipheral edges thereof. The both ends of the connecting belts 70 arestitched to the inner peripheral surfaces (surface facing the inside ofthe airbag in the finished state as an airbag product) of the frontinner panels 22, 24 and the front outer panels 26, 28, which aredisposed outside in this state, respectively.

[0052] Accordingly, a reversed intermediate airbag product ismanufactured. Then, the intermediate airbag product is reversed throughthe opening 60 formed at the seam allowance 44. The airbag 10 iscompleted by stitching the joint allowances 48, 50 of the seamallowances 44, 46 together by the seams 52. When the joint allowances48, 50 are stitched together, the opening 60 is closed by the seams 52.

[0053] As described above, the airbag 10 is formed of a plurality of thepanels. Thus, although the outer surface of the airbag 10 has a largearea and a complex shape, the airbag may be manufactured from the panelshaving relatively small area without wasting a material.

[0054] In this embodiment, the left half airbag 12 and the righthalf-airbag 14 are joined at the seam allowances 44, 46 of the rearinner panel 18 and the front inner panels 22, 24. Accordingly, it is notnecessary to use a tie panel for connecting the right half airbag 12 andthe left half airbag 14 in addition to the respective panels 18, 22, 24,thereby reducing a cost for constructing the airbag 10.

[0055] In this embodiment, the pair of the slits 54 is provided in therear outer panel 20 of the communicating portion 16 as openings for aninflator, and the rod-shaped inflator 56 is inserted into the slits 54so that the inflator 56 is disposed in the communicating portion 16.When the openings are formed into a slit-shape, the connecting strengthof the inflator 56 to the airbag 10 is high.

[0056] In this embodiment, the opening 60 is formed in the seamallowance 44 for reversing the airbag product in the process ofmanufacturing the airbag as described above. Thus, even when theintermediate airbag product can not be reversed easily via the vent holeor the opening for an inflator, in particular, even when the openingsfor an inflator are formed in a slit-shape as in this embodiment, theintermediate airbag product can be reversed easily via the opening 60.The opening 60 is closed with the seams 52 when the joint allowances 48,50 are stitched together. Thus, the gas introduced from the inflator 56into the right half airbag 12 and the left half airbag 14 does not leakthrough the opening 60.

[0057] In the embodiment, the both side surfaces of the right halfairbag 12 and the left half airbag 14 are connected with each other bythe connecting belts 70. Alternatively, the side surfaces may beconnected by two or more connecting belts. It is also possible toconnect upper and lower surfaces of the right half airbag 12 and theleft half airbag 14 by connecting belts to constrain vertical lengths ofthe right half airbag 12 and the left half airbag 14 when the airbag isdeployed. In this case, the capacities of the right half airbag 12 andthe left half airbag 14 are reduced, and thus even when an inflator hasa small capacity, the right half airbag 12 and the left half airbag 14can be deployed sufficiently quickly.

[0058] In addition to the lateral direction and the vertical direction,it is further possible to connect the surfaces of the right half airbag12 and the left half airbag 14 opposing obliquely when viewed from theoccupant with connecting belts so that the lengths of the right halfairbag 12 and the left half airbag 14 in the oblique direction areconstrained.

[0059] According to another embodiment of the present invention, anairbag 10A includes the connecting belts for constraining both thelateral widths and the vertical widths of the left half airbag and theright half airbag. FIG. 5 is a cross-sectional perspective view of theairbag 10A having a portion where connecting belts are provided. Theairbag 10A also includes the right half airbag 12 to be deployed on theright front side of the occupant, the left half airbag 14 to be deployedon the left front side of the occupant, and the communicating portion 16communicating the end portions of the right half airbag 12 and the lefthalf airbag 14 with each other. Connecting belts 74 as constrainingmeans are provided in the right half airbag 12 and the left half airbag14 for constraining the lateral widths and the vertical widths of theright half airbag 12 and the left half airbag 14, respectively.

[0060] Each of the connecting belts 74 includes four arm portions 74 a,74 b, 74 c, 74 d extending in four directions. As shown in FIG. 5, thearm portions 74 a, 74 c extend laterally inside the right half airbag 12and the left half airbag 14, and distal ends thereof are stitched to theright and left side surfaces of the right half airbag 12 and the lefthalf airbag 14, respectively. The arm portions 74 b, 74 d extendvertically inside the right half airbag 12 and the left half airbag 14,and distal ends thereof are stitched on the upper surfaces and the lowersurfaces of the right half airbag 12 and the left half airbag 14.

[0061] In the airbag 10A, when the right half airbag 12 and the lefthalf airbag 14 are deployed, the arm portions 74 a, 74 c constrain theboth side surfaces of the right half airbag 12 and the left half airbag14 in a direction away from each other. Likewise, the arm portions 74 b,74 d constrain the upper surfaces and the lower surfaces of the righthalf airbag 12 and the left half airbag 14 in a direction away from eachother. Accordingly, both of the lateral widths and the vertical widthsof the right half airbag 12 and the left half airbag 14 are constrained.

[0062] In FIG. 5, the both side surfaces of the right half airbag 12 andthe left half airbag 14 are connected with each other by thesubstantially horizontal arm portions 74 a, 74 c of the connecting belts74. The upper surfaces and the lower surfaces thereof are connected bythe substantially vertical arm portions 74 b, 74 d. It is also possibleto constrain the vertical and lateral widths of the right half airbag 12and the left half airbag 14 by connecting the upper right surfaces andthe lower left surfaces of the right half airbag 12 and the left halfairbag 14 by the arm portions 74 a, 74 c, and by connecting the upperleft surfaces and the lower right surfaces thereof by the arm portions74 b, 74 d.

[0063] In the embodiment described above, the connecting belts are usedas means for constraining the widths of the left half airbag and theright half airbag. Alternatively, it is possible to constrain the widthsof the left half airbag and the right half airbag by joining the panelsconstituting the left and the right side surfaces of the left halfairbag and the right half airbag directly with each other. FIG. 6 is across sectional perspective view of an airbag in which panels are joineddirectly with each other.

[0064] As shown in FIG. 6, an airbag 10B includes the right half airbag12 to be deployed on the right front side of the occupant, the left halfairbag 14 to be deployed on the left front side of the occupant, and thecommunicating portion 16 communicating the end portions of the righthalf airbag 12 and the left half airbag 14 with each other. Left andright side surfaces of the right half airbag 12 are formed of an innerpanel 24A and an outer panel 28A. Left and right side surfaces of theleft half airbag 14 are formed of an inner panel 22A and an outer panel26A. The panel 22A and the panel 26A are superimposed, and the panel 24Aand the panel 28A are superimposed. Peripheral edges thereof arestitched with each other by seams 40A, 42A to form a bag-shape.

[0065] As shown in FIG. 6, center portions of the inner panels 22A, 24Aand the outer panels 26A, 28A are stitched directly with each other byseams 76. Accordingly, the portions stitched by the seams 76 prevent theinner panels 22A, 24A and the outer panels 26A, 28A from moving in thedirection away from each other, so that the lateral widths of the righthalf airbag 12 and the left half airbag 14 are constrained.

[0066] In this embodiment, the portions stitched by the seams 76 have anannular shape, and are not connected to the seams 40A, 42A around theperipheral edges of the inner panels 22A, 24A and the outer panels 26A,28A.

[0067] In the airbag 10B, the panels 22A, 26A and the panels 24A, 28Aconstituting the both side surfaces of the right half airbag 12 and theleft half airbag 14 are stitched directly with each other by the seams76, respectively. Accordingly, the portions of the panels 22A, 26A, andthe panels 24A, 28A stitched by the seams 76 do not move away from eachother. Therefore, the capacities of the right half airbag 12 and theleft half airbag 14 when deployed are sufficiently reduced. Even when aninflator has a small capacity, the right half airbag 12 and the lefthalf airbag 14 can be deployed very quickly.

[0068] The features of the portions stitched by the seams 76, such asconfiguration, number, arrangement, or the like, are not limited tothose shown in the drawings, and may be modified as needed.

[0069] According to a further embodiment of the present invention, theleft half airbag and the right half airbag may have narrow portionstighten with a belt or the like wrapping around an outer periphery ofthe left half airbag and the right half airbag, so that the capacitiesof the left half airbag and the right half airbag are reduced when theairbag is deployed. FIG. 7(a) is a perspective view of the airbag in astate of being tightened by a belt, and FIG. 7(b) is a cross sectionalperspective view of a portion at which the belt is provided.

[0070] As shown in FIGS. 7(a) and 7(b), an airbag 10C includes the righthalf airbag 12 to be deployed on the right front side of the occupant,the left half airbag 14 to be deployed on the left front side of theoccupant, and the communicating portion 16 communicating the endportions of the right half airbag 12 and the left half airbag 14 witheach other. The both side surfaces of the right half airbag 12 areformed of the inner panel 24A and the outer panel 28A. The both sidesurfaces of the left half airbag 14 are formed of the inner panel 22Aand the outer panel 26A. The inner panels 22A, 24A and the outer panels26A, 28A are superimposed, and the peripheral edges thereof are stitchedwith each other by the seams 40A, 42A to form a bag-shape.

[0071] The center portions of the panel 22A and the panel 26A arestitched by the seams 76 with each other, and the center portions of thepanel 24A and the panel 28A are stitched by the seams 76 with eachother. The lateral widths of the right half airbag 12 and the left halfairbag 14 are constrained by stitching of the seams 76 when the airbagis inflated.

[0072] In this embodiment, a tightening belt 78 extends around the outerperiphery of the right half airbag 12 and the left half airbag 14, sothat the center portions of the right half airbag 12 and the left halfairbag 14 are constrained when the airbag is inflated. As shown in FIG.7(a), the tightening belt 78 is laminated in three layers at the seams76 relative to the outer panels 26A, 28A and the inner panels 22A, 24A,and is stitched by the seams 76, so that the tightening belt 78 isattached to the airbag 10C.

[0073] In the airbag 10C, the capacities of the right half airbag 12 andthe left half airbag 14 are small when the airbag is inflated. Thus, itis possible to deploy the airbag sufficiently quickly even when aninflator has a small capacity.

[0074] In the embodiments described above, the both side surfaces of theleft half airbag and the right half airbag are connected or joined witheach other, so that the capacities of the left half airbag and the righthalf airbag are reduced when the airbag is deployed.

[0075] According to a still further embodiment of the present invention,outer side surfaces of the left half airbag and the right half airbagare joined with each other to constrain their movements in the directionaway from each other, so that the capacities of the left half airbag andthe right half airbag are reduced when the airbag is deployed. FIG. 8(a)is a perspective view of an airbag having such an arrangement, and FIG.8(b) is a cross sectional view (rear view) taken along line 8(b)-8(b) inFIG. 8(a).

[0076] As shown in FIGS. 8(a) and 8(b), an airbag 10D includes the righthalf airbag 12 to be deployed on the right front side of the occupant,the left half airbag 14 to be deployed on the left front side of theoccupant, and the communicating portion 16 communicating the endportions of the right half airbag 12 and the left half airbag 14 witheach other. The both side surfaces of the right half airbag 12 areformed of the inner panel 24A and the outer panel 28A. The both sidesurfaces of the left half airbag 14 are formed of the inner panel 22Aand the outer panel 26A. The panel 22A and the panel 26A aresuperimposed, and the panel 24A and the panel 28A are superimposed. Theperipheral edges thereof are stitched with each other by the seams 40A,42A to form a bag-shape. The center portions of the panel 22A, 26A, andthe center portions of the panels 24A, 28A are stitched by seams 80 witheach other to constrain the lateral widths of the right half and theleft half airbags 12, 14 when the airbag is deployed.

[0077] In this embodiment, the portion stitched by the seam 80 hassubstantially a square loop. The right half airbag 12 and the left halfairbag 14 have belt insertion holes 82 passing through the inner panels22A, 24A and the outer panels 26A, 28A at an inside of the square loop.As shown in FIG. 8(b), a connecting belt 84 passes through the beltinsertion holes 82 so as to pass through both of the right half airbag12 and the left half airbag 14. Both ends of the connecting belt 84 arejoined to the outer surfaces of the outer panel 28A of the right halfairbag 12 and the outer panel 26A of the left half airbag 14, andstitched to the panels 26A, 28A by seams 86, respectively.

[0078] In the airbag 10D, the panels 22A, 26A are directly stitched witheach other, and the panels 24A, 28A are directly stitched with eachother by the seams 80. Accordingly, the portions stitched by the seams80 do not move away from each other. Also, the outer panel 28A of theright half airbag 12 is connected to the outer panel 26A of the lefthalf airbag 14 by the connecting belt 84. Accordingly, the panels do notmove away from each other more than a length of the connecting belts 84.Therefore, the capacities of the right half airbag 12 and the left halfairbag 14 are significantly reduced when the airbag is deployed.

[0079] The embodiments described above are just examples of the presentinvention, and the present invention is not limited to the embodimentsshown in the drawings. For example, the right half airbag 12 and theleft half airbag 14 are communicated at the base side thereof in theembodiments. Alternatively, both of the bags may be formed separately.The left half airbag and the right half airbag may be deployed byseparate inflators. The midsections of the left half airbag and theright half airbag may be connected with each other by a panel, a string,or a net.

[0080] In the present invention, the left half airbag and the right halfairbag may be formed either in a symmetrical shape or in an asymmetricalshape. The capacities of the left half airbag and the right half airbagmay be either the same or different.

[0081] According to a still further embodiment of the present invention,as shown in FIG. 9, the airbag at a side of an A pillar (a right halfairbag 12A in FIG. 9) may include an inclined upper portion along acabin to avoid contact with the A pillar, a windshield, or a side windowas much as possible. Connecting belts 88 connect the both side surfacesof a right half airbag 12A and a left half airbag 14A with each otherfor constraining the widths of the right half airbag 12A and the lefthalf airbag 14A, respectively, when the airbag is deployed.

[0082] According to a still further embodiment of the present invention,as shown in FIG. 10, the airbag may be formed so that the lateral widthdecreases gradually upwardly when the airbag is deployed. As shown inFIG. 10, the both side surfaces of the right half airbag 12B and theleft half airbag 14B are connected with each other by connecting belts90, respectively, so that the widths of the right half airbag 12B andthe left half airbag 14B are constrained when the airbag is deployed.

[0083] As described above, according to the present invention, theairbag and the airbag apparatus include the left half airbag and theright half airbag to be deployed sufficiently quickly even when thecapacity of the inflator is small. According to the present invention,the airbag and the airbag apparatus include the left half airbag forreceiving the left thorax of the occupant, the right half airbag forreceiving the right thorax thereof, and the space between the both bagsfacing the portion around the breastbones of the occupant. Furthermore,according to the present invention, the airbag and the airbag apparatusinclude the left half airbag and the right half airbag to be deployedsmoothly and symmetrically from the early stage of deployment.

[0084] While the invention has been explained with reference to thespecific embodiments of the invention, the explanation is illustrativeand the invention is limited only by the appended claims.

What is claimed is:
 1. An airbag for protecting an occupant, comprising:a left half airbag to be deployed on a left side of the occupant, aright half airbag to be deployed on a right side of the occupant, andwidth constraining means attached to the left half airbag and right halfairbag, respectively, for constraining lateral widths thereof when theleft half airbag and the right half airbag are inflated.
 2. An airbagaccording to claim 1, wherein said width constraining means is formed ofa string.
 3. An airbag according to claim 1, wherein said widthconstraining means includes joining means for directly joining panelsfor constituting the left half airbag and the right half airbag,respectively.
 4. An airbag according to claim 1, wherein said left halfairbag and right half airbag have distal ends facing the occupant, saiddistal ends being separated from each other so that a space is formedbetween the distal ends facing the occupant when the left half airbagand the right half airbag are inflated.
 5. An airbag according to claim1, wherein said left half airbag is connected to the right half airbagat midsections thereof in a direction that the left half airbag and theright half airbag deploy.
 6. An airbag according to claim 1, furthercomprising vertical width constraining means for constraining verticalwidths of the left half airbag and the right half airbag when the lefthalf airbag and the right half airbag are deployed.
 7. An airbagaccording to claim 1, wherein at least one of said left half airbag andsaid right half airbag includes an inclined upper portion so that theone of the left half airbag and the right half airbag does not contactan interior of a vehicle when the left half airbag and the right halfairbag are inflated.
 8. An airbag according to claim 1, wherein at leastone of said left half airbag and said right half airbag includes aportion having a thickness gradually decreasing upwardly when the lefthalf airbag and the right half airbag are inflated.
 9. An airbagaccording to claim 1, wherein said left half airbag and said right halfairbag have distal ends thereof separated by a distance of 150-350 mmwhen the left half airbag and the right half airbag are deployed.
 10. Anairbag according to claim 1, further comprising a base communicatingwith the left and right half airbags, said left and right half airbagseparately projecting outwardly from the base.
 11. An airbag apparatuscomprising the airbag according to claim 1 and an inflator for inflatingthe airbag.